The present invention relates to a method of controlling hard disk units accommodated in a disk array system.
A disk array system is ordinarily arranged to accommodate a plurality of hard disk units. One of the features of the disk array system utilized so far is that when any trouble is caused in the hard disk units accommodated in the disk array systems, the target hard disk unit is removed from the system and a hard disk unit with no failure is accommodated in the place where the problematic hard disk unit suffering from a problem is housed, whereby it becomes possible to restore the data stored in the system. For example, Gazette of U.S. Pat. No. 4,870,643 discloses a matter relating to the data restoration upon exchanging a hard disk unit.
Further, according to the invention disclosed in Gazette of U.S. Pat. No. 4,870,643, it is assumed that, ordinarily, no more than one hard disk unit will become problematic at a time, so that it is unnecessary to manage on the disk control side information of each hard disk unit actually inserted. That is, if a hard disk unit is once removed at a position from the disk array system and then inserted into a position different from that position (e.g., the removed hard disk is inserted into a slot adjacent to the slot where the hard disk unit was inserted), it becomes impossible to take data coordination, with the result that information stored in the disk can be destroyed.
As described above, for example, if there are a plurality of ports under control of the controller and a plurality of hard disk units are connected to the ports, or alternatively, balance is taken between the number of ports to be utilized and the hard disk units coupled to the ports in order that the transfer efficiency is improved, in a conventional manner, data stored in the hard disk units shall be wholly reserved as backup data before rearranging the hard disk units, and thereafter the data is loaded in the system to build the disk array system.
Further, the above disk array system can encounter the following problem. That is, when the disk array system is moved from one place to another, for example, all of the hard disk units may be taken out from a housing of the disk array system and each of the disk array system components is transported separately so that the hard disk unit can be protected from vibration or the like upon transportation of the components. In this case, if the disk array system is large sized, the number of hard disk units may reach one hundred or more. Therefore, when the disk array system components are transported to the destination and the hard disk units are inserted into a housing of the disk array system to reconstruct the disk array system, it is not guaranteed that all of the hard disk units are inserted into their correct position of the housing. If a hard disk unit is inserted into the housing at an erroneous position, data can be destroyed in the worst case. Unlike the ordinary case where only one hard disk unit suffers from failure, it is unrealistic to try all of the combinations between the hard disk units and respective insertion slots of the disk array system housing.
According to one means of the present invention for solving the above-identified problem, RAID logic arrangement information and the hard disk unit physical position information are subjected to mapping and the resulting information is managed by a disk controller or a host controller thereof. According to the arrangement, even if the hard disk unit physical position is changed, information mapping is retried in accordance with the existing mapped information. Thus, data coordination can be guaranteed.
Further, according to another means of the present invention, information of the hard disk units accommodated in the disk array system under the administration of the disk controller is rearranged to indicate positions based on an n-dimensional coordinate system information, and the resulting information is stored in each of the hard disk units. When the hard disk unit is inserted, the n-dimensional coordinate system information is read from each of the hard disk units. If it is detected that there is difference between the current coordinate system information and coordinate system information read from each of the hard disk units, then information of the arrangement of the hard disk units before removal and that after the insertion are compared with each other and the data link is reconstructed. Thus, information can be restored.
Furthermore, according to still another means of the present invention, the disk array system writes an identification number in each of the hard disk units so that each hard disk unit has its inherent number, and an assignment table indicating assignment relation between the administration number and actual n-dimensional physical position coordinate is displayed. Therefore, a user can confirm a correct position at which the hard disk unit is to be inserted in accordance with the result of display. Alternatively, the user can be given a command message about the physical position according to which the hard disk unit insertion is changed. Thus, information can be restored.
According to the above technologies, even if the hard disk unit to be exchanged is changed in its position at which the hard disk unit is inserted, data can be guaranteed and the data need not undergo backup upon changing the arrangement of the hard disk units. Further, if many hard disk units are transported in a manner in which each hard disk unit is separated from the housing of the disk array system, data can be protected from damage due to an erroneous insertion position upon assembling the disk array system at the destination of transportation.
Moreover, according to the present invention, if the disk array system has an arrangement including one disk controller and two or more hard disk units under administration of the disk controller, and the hard disk units are removed from the disk array system and again inserted into the same, then the user can insert the hard disk units into the disk array system without any consciousness about the arrangement of the hard disk units before they are removed from the housing. Thus, data can be protected from damage due to incorrect position of insertion.
For example, when the housing into which the hard disk units are inserted is to be exchanged, the above-described mapping function can be utilized. If the housing is exchanged in this manner, the hard disk units can be accommodated in other housing without sheltering or installing the data.
When the disk array system is transported and the hard disk units are removed from the housing of the disk array system for the sake of security of the transport work, for example, the user can insert the hard disk units into the disk array system without any consciousness about the arrangement of the hard disk units before removal operation at the destination of the transportation. Therefore, improvement in working efficiency can be expected.
Furthermore, if the mapping information is displayed and the function for verifying the actual insertion position is effected, the user can positively confirm the position at which the hard disk unit was inserted. Therefore, trouble caused by moving the disk array system can also be prevented.
Though some merits or advantages deriving from the present invention have been listed above, at least some of them can be expected by implementing the present invention. Two or more merits or advantages can be expected depending on the specification of the disk array system of arrangement of the target disk array system. However, some of the merits or advantages may not become conspicuous in spite of the fact that the present invention is implemented. In this case, it is to be noted that, if there is no apparent merit or advantage on a disk array system, which fact does not decisively mean that the present invention is not applied to the disk array system.